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1 Shrimp Trawl Various types of gear are used to capture shrimp including but not limited to cast nets, haul seines, stationary butterfly nets, wing nets, skimmer nets, traps, and beam trawls. The otter trawl with various modifications, is the dominant gear used in offshore. A basic otter trawl consists of a heavy mesh bag with wings on each side designed to funnel the shrimp into the cod end or tail bag. A pair of otter boards or trawl doors positioned at the end of each wing hold the mouth of the net open by exerting a downward and outward force at towing speed (NMFS, 2002). Figure 1. shows a typical otter trawl configuration. Figure 1. General shrimp trawl configuration (NMFS, 1992). Shrimp trawl nets are usually constructed of nylon or polyethylene mesh webbing, with individual mesh sizes ranging from as small as 1-1/4" to 2". The sections of webbing are assembled according to the size and design (usually flat, balloon, or semi-balloon) of trawl desired, which affects the width and height of the trawl s opening and its bottomtending characteristics. The tongue or mongoose design incorporates a triangular tongue of additional webbing attached to the middle of the headrope pulled by a center towing cable, in addition to the two cables pulling the doors. This configuration allows the net to spread wider and higher than conventional nets and as a result has gained much popularity for white shrimp fishing. N-1

2 Try nets are small otter trawls about 12 to 16 feet in width that are used to test areas for shrimp concentrations. These nets are towed during regular trawling operations and lifted periodically to allow the fishermen to assess the amount of shrimp and other fish and shellfish being caught. These amounts in turn determine the length of time the large trawls will remain set or whether more favorable locations will be selected. Until the late 1950s, most shrimp vessels pulled single otter trawls, ranging from 80 to 100 feet in width, directly astern of the boat. Double-rig trawling was introduced into the shrimp fleet during the late 1950s. The single large trawl was replaced by two smaller trawls, each 40 to 50 feet in width, towed simultaneously from stoutly constructed outriggers located on the port and starboard sides of the vessels. The advantages of double-rig trawling include: (1) increased catch per unit of effort, (2) fewer handling problems with the smaller nets, (3) lower initial gear costs, (4) a reduction in costs associated with damage or loss of the nets, and (5) greater crew safety. In 1972, the quad rig was introduced in the shrimp fishery, and by 1976 it became widely used in the EEZ of the western Gulf. The quad rig consists of a twin trawl pulled from each outrigger. One twin trawl typically consists of two 40- or 50-foot trawls connected to a center sled and spread by two outside trawl 9 doors. Thus, the quad rig with two twin trawls has a total spread of feet versus the total spread of 110 feet in the old double rig of two 55- foot trawls. The quad rig has less drag and is more fuel efficient. The quad rig is the primary gear used in federal waters by larger vessels. Smaller boats and inshore trawlers often still use single- or double-rigged nets. In recent years, the skimmer trawl has become a major gear in the inshore shrimp fishery in the northern Gulf and also has some use in inshore NorthCarolina. N-2

3 Bycatch Reduction Devices A. Extended Funnel BRD The extended funnel BRD (Figure 2) consists of an extension with large-mesh webbing in the center (the large-mesh escape section) and small-mesh webbing on each end held open by a semi-rigid hoop. A funnel of small-mesh webbing is placed inside the extension to form a passage for shrimp to the codend. It also creates an area of reduced water flow to allow for fish escapement through the large mesh. One side of the funnel is extended vertically to form a lead panel and area of reduced water flow. There are two sizes of extended funnel BRDs, a standard size and an inshore size for small trawls. Figure 2. Large Mesh Extended Funnel (Watson, 1995) B. Expanded Mesh BRD The expanded mesh BRD is constructed and installed exactly the same as the standard size extended funnel BRD, except that one side of the funnel is not extended to form a lead panel. N-3

4 C. Fisheye BRD The fisheye BRD (Figure 3) is a cone-shaped rigid frame constructed from aluminum or steel rod of at least 1/4 inch diameter, which is inserted into the codend to form an escape opening. Fisheyes of several different shapes and sizes have been tested in different positions in the codend. Figure 3. Fisheye Bycatch Reduction Device (Watson, 1995)` N-4

5 Turtle Excluder Device The Turtle Excluder Device or TED is a grid of bars with an opening either at the top or the bottom. The grid is fitted into the neck of a shrimp trawl. Small animals like shrimp slip through the bars and are caught in the bag end of the trawl. Large animals such as turtles and sharks, when caught at the mouth of the trawl, strike the grid bars and are ejected through the opening (taken from Photo courtesy of NMFS). References NMFS Evaluation of bycatch reduction devices. Sampling protocol manual for data collection. NMFS, SEFSC. September 14, pp. NMFS Endangered Species Act Section 7 Consultation, Biological Opinion on Shrimp Trawling in the Southeastern United States, Under the Sea Turtle Conservation Regulations and as Managed Under the Fishery Management Plans for Shrimp in the South Atlantic and Gulf of Mexico Watson, J.W Summary Report on the status of bycatch reduction device development. Presented to the South Atlantic Fishery Management Council, April N-5

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